Such electromagnetic valves are known for example from the printed documents U.S. Pat. No. 5,197,710, U.S. Pat. No. 5,458,151 and U.S. Pat. No. 5,452,738.
The known electromagnetically actuated valves or solenoid-actuated valves are used to control the flow of compressed gases into the gas cylinder or out of the gas cylinder. Gas cylinders for gas-powered vehicles hold the combustion gas at a pressure above atmospheric, for example between 2 and 260 bar. The said electromagnetic valves allow a bi-directional gas stream, on the one hand, during refuelling into the gas cylinder and, on the other hand, during driving mode of the engine out of the gas cylinder towards the engine. During driving mode, the gas flows from the interior of the gas cylinder at high pressure through a connection channel into the supply line to the pressure reducer, in which the pressure is reduced to the required injection pressure of the engine, e.g. 2 to 8 bar. During refuelling, the gas flows in the opposite direction from a refuelling system though the same connection channel into the gas cylinder. During the refuelling operation, the refuelling channel of the refuelling system has a high internal pressure, e.g. 200 to 260 bar. The empty gas cylinder has a lower internal pressure until it has been completely filled with gas and reaches the pressure of the refuelling system.
In addition to their function of reliably regulating the gas flow in the two different operating situations, such electromagnetic valves have to meet high safety standards. For this reason, in the cited US patents it was proposed that the cavity for receiving the shut-off piston and the electromagnetic control elements of the valve be disposed inside the threaded portion and/or the portion of the valve body projecting into the gas cylinder. The valve body is made of a relatively non-rigid material, for example brass, whereas the gas cylinder is made of very hard material, usually steel or composite material. By shifting the shut-off piston and the control elements into portions of the valve body that are situated inside the hard wall of the gas cylinder, the safety of the valve in the event of a crash, i.e. in the event of powerful impacts upon the valve owing to an accident, is dramatically increased compared to valves having functional elements situated outside of the cylinder. To disassemble the valves for maintenance or cleaning purposes, the valve body first has to be unscrewed from the gas cylinder to gain access to the functional elements of the valve, namely the shut-off piston and the control elements, from the rear of the valve body situated in the gas cylinder.
Accordingly, it is desirable to facilitate the disassembly and assembly of a valve of the described type.